The Ascertainment Core will provide centralized, screening, clinical and psychological testing, and blood draw for all projects of the program. It will be managed. It will be managed and staffed by Dr. Lainhart (PI), Dr. Miller (Investigator) and 2.6 FTE positions, including a coordinator, nurse, research assistants and community liaison. Regular contact between investigators in the Ascertainment Core and Component Projects will ensure Ascertainment procedures are efficient and fulfilling the needs of the Components and that data and subject safety are maintained. Subjects will be recruited from previous studies (including the P01) and 4 community sites. Many of the new subjects needed are between the ages of 3 and 6; thus, 2 sites that serve preschool-age children with autism are included. Interested subjects will complete a screening questionnaire available by website or mail and contact that Program. The Ascertainment Core will then conduct several levels of screening including review of questionnaires, followup telephone interviews if necessary, collection of medical records, and coordination of pedigree linkage analysis by the UPDB. It will prioritize subject recruitment to those eligible for multiple components, and track participation across projects. It will also conduct the extensive assessments required for participation in site-specific and network studies, including diagnostic assessment, psychological testing, language, motor ability, family history, medical and pregnancy histories, etc. Years 1-3 will be devoted to the bulk of subject recruitment and data collection. Years 3-5.3 will be devoted to retesting and re-scanning subjects in the Imaging Component longitudinal study and data analysis. Issues related to use of human subjects, diverse samples, and data monitoring and safety are addressed.